Obsidian hydration dating (or OHD) is a scientific dating technique, which uses the understanding of the geochemical nature of the volcanic glass (a silicate) called obsidian to provide both relative and absolute dates on artifacts.Obsidian outcrops all over the world, and was preferentially used by stone tool makers because it is very easy to work with, it is very sharp when broken, and it comes in a variety of vivid colors, black, orange, red, green and clear. The age of the pottery, in principle, may then be determined by the relation Age = Accumulated dose / Dose per year Although conceptually straightforward, TL has proven to to be far from simple in practice. Should I be concerned about artificial irradiation? If the radioactivity of the pottery itself, and its surroundings, is measured, the dose rate, or annual increment of dose, may be computed. Warning about fakes using ancient materials What about airport x-rays and radiography? Thus, when one measures dose in pottery, it is the dose accumulated since it was fired, unless there was a subsequent reheating. When pottery is fired, it loses all its previously acquired TL, and on cooling the TL begins again to build up.They used pottery and other materials in sites to date 'relatively'.
By measuring the thickness you can easily determine if one artifact is older than another (relative age).If you can determine the rate at which water diffuses into the glass for that particular chunk of obsidian (that's the tricky part), you can use OHD to determine the absolute age of objects.The relationship is disarmingly simple: Age = DX2, where Age is in years, D is a constant and X is the hydration rind thickness in microns.Because of the distortions and lies spread by fundamentalists about scientific dating there is a need for a centralized source of information on the topic.A few examples of such lies are presented at the very bottom of this page.